1. Field of the Invention
This invention relates to computer systems and, more particularly, to computer systems which share data information and processing capabilities.
2. Background of the Invention
Before the development and widespread use of the personal computer, users would typically tap into a large mainframe computer through a terminal, such as a keyboard alone or with a monitor or other visual display, at the user's location. Such an arrangement gave a user the processing capabilities and data sharing of the powerful mainframe computer, and multiple users could access the mainframe through time-sharing or other arrangements. However, the user had little or no control over the application software included in the mainframe computer and the expense involved in purchasing a mainframe computer was prohibitive to all but the larger corporations.
With the advent of the personal computer, powerful computing capabilities have been brought to a user's desk. Many users of large mainframe computers have decided to decentralize their large machines for smaller desktop computers used as workstations. However, standalone personal computers have a drawback in that data cannot be shared and application programs residing in other personal computers in an organization or elsewhere cannot be utilized without additional modifications. The desire to communicate and share information with other users led to the development of personal computer networks.
Existing local area networks (LAN) interconnect a variety of workstations over a common cabling system. This enables the workstations to communicate with each other and to share access to computing resources, such as mainframe or other databases, laser printers and file servers. Transmission of information on the LAN to and from these devices, and to other workstations, is governed by a network interface card or logic embedded within the computer workstation, and attached to the LAN. These workstations are interconnected by communication concentrators, typically located at a centralized location. In addition, a typical prior art LAN requires a file server or other mechanism for controlling the operation of the LAN and data flowing therein. To function properly, the connecting devices of the LAN must obey rules or protocols that govern access to and communications with the network. Some of the communication protocols which have been developed include the Ethernet, Token Ring, Appletalk, Fiber Distributed Data Interface (FDDI) and ARCNET serial bus networks, and the VME, Multibus and Futurebus parallel bus networks.
In addition to the various network protocols, users may employ different cabling media, such as twisted wire cables, fiber optics, phone lines and infrared light and radio signals, to connect the workstations to the network. A user may find it necessary to use an external transceiver unit to convert a network interface card to a different cabling medium in order to provide physical access to the network.
These prior art networks, while functioning adequately for many applications, do have several drawbacks. Initially, each user or user location must include a computer processing unit along with, at least, a keyboard and monitor to supply the computing capabilities to the user and provide access to the network. In addition, expensive network cabling media must extend from user to user along the network. Typically, this expensive cabling media extends over great distances as users are located physically in widely separated areas. The use of separate processing units at each user's location, as well as the expensive and lengthy cabling media, renders typical computer networks rather expensive. In addition, the length of the network cabling media limits the speed at which the network can be operated.
It is, accordingly, an object of the present invention to provide a computer networking arrangement which includes the processing and data sharing capabilities of prior networks, but which is faster in operation and includes fewer computer processors per user location than prior systems.
It is a further object to provide such a computer network in a system which is easy to configure and operate, is readily modifiable for different network requirements, and can be easily changed to accommodate the rapid changes in network protocols, computer processing capabilities and the like.